New Derivatives of Dehydroacetic Acid: Synthesis of 2-Polyfluoroalkyl-7-methylpyrano[4,3-b]pyran-4,5-diones.

The condensation of dehydroacetic acid with RFCO2Et in the presence of LiH in THF afforded fluorine-containing 3-acetoacetyl-4-hydroxy-6-methylpyrones, which underwent cyclization to 2-polyfluoroalkyl-7-methylpyrano[4,3-b]pyran-4,5-diones on treatment with concentrated sulfuric acid at room temperature.